Transverse momentum balance of dijets in Xe+Xe collisions at the LHC

We present a theoretical study of the medium modifications on the $p_{\rm T}$ balance ($x_{\rm J}$) of dijets in Xe+Xe collisions at $\sqrt{s_{\rm NN}}=5.44$ TeV. The initial production of dijets is carried out by the POWHEG+PYTHIA8 prescription, which matches the next-to-leading order (NLO) QCD matrix elements with the parton shower (PS) effect. The in-medium evolution in nucleus-nucleus collisions is described by the SHELL model with a transport approach. The theoretical results of the dijet $x_{\rm J}$ in Xe+Xe collisions exhibit more imbalanced distributions than that in p+p, consistent with the recently reported ATLAS data. By utilizing the Interleaved Flavor Neutralisation, an infrared-and-collinear-safe jet flavor algorithm, to identify the flavor of the reconstructed jets, we classify dijets processes into three categories: gluon-gluon ($gg$), quark-gluon ($qg$) and quark-quark ($qq$), and investigate the respective medium modification patterns and fraction changes of the $gg$, $qg$, and $qq$ components of the dijet sample in Xe+Xe collisions. It is shown that the $qg$ component plays a key role in the increased imbalance of the dijet $x_{\rm J}$, and especially the $q_1g_2$ (quark-jet-leading) dijets experience more significant asymmetric energy loss than the $g_1q_2$ (gluon-jet-leading) dijets as traversing the QGP. By comparing the $\Delta \langle x_{\rm J}\rangle$ of inclusive, $c\bar{c}$ and $b\bar{b}$ dijets in Xe+Xe collisions, we observe $\Delta \langle x_{\rm J} \rangle_{\rm incl.}>\Delta \langle x_{\rm J} \rangle_{\rm c\bar{c}}>\Delta \langle x_{\rm J} \rangle_{\rm b\bar{b}}$. Moreover, $\rho_{\rm Xe, Pb}$, the ratios of nuclear modification factors of dijets in Xe+Xe to that in Pb+Pb, are calcualted, which indicates that the yield suppression of dijets in Pb+Pb is more pronounced than that in Xe+Xe due to the larger radius of the lead nucleus.